In certain work environments such as for example, healthcare workers involved with x-ray equipment, technicians, doctors and other operators of x-ray equipment including computed tomography operators, there is potential for exposure to ionizing radiation. Personnel in these areas must be constantly monitored to make sure that they are not exposed to radiation above specified limits.
The effect of exposure to ionizing radiation in humans is cumulative and the U.S. Government through the Occupational Safety and Health Administration has set acceptable limits for an average exposure over time (e.g., 10 rems/year for healthcare workers and 5 rems/year for the general population wherein rein is defined as roentgen equivalent man). To monitor worker exposure, workplaces require the use of film badges that are worn by the personnel. The film is sensitive to the ionizing radiation and after a certain interval of usage, the film is sent to a laboratory for analysis. The information concerning personnel exposure is thus not readily available and actual information concerning an exposure may not be received until months after the exposure had occurred. No information would be available at the immediate time of exposure.
Various types of portable monitoring equipment have become available such as, for example, Geiger counters and ionization chambers that provide information concerning an instantaneous value of a radiation field. These devices are large and cumbersome and cannot be worn by personnel in the working environment. Other devices have been developed utilizing sophisticated crystals and semiconductors in which exposures to photon radiation are converted into electronic and audible signals to indicate that threshold levels have been exceeded. Other personal dosimeters include complicated time measuring devices that provide additional information to the user or depend on a one-to one relationship on the energy spectrum of a radiation capable of being received by a detector.
Many of these devices provide instantaneous readings of exposure levels but are cumbersome to wear and are also very expensive. Often these devices require a detective element to be charged or regenerated. Other devices require many mechanical parts that are susceptible to breakage. Finally, many of these devices do not provide for any test features to assure that the equipment is in proper working order. Thus many of these types of personal dosimeters have not been commercially successful.
There is a need for a personal detection device to monitor exposure to ionizing radiation that provides immediate information concerning exposure over the acceptable threshold limit that is lightweight and easy to operate. There is also a need for a detection device that provides for monitoring cumulative exposure to radiation in addition to providing immediate information.